Air-conditioning apparatus

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Solution Overview

Problem

Air conditioners face challenges in maintaining a desirable gas-liquid two-phase state of refrigerant in the liquid-refrigerant connection pipe while suppressing the increase in compressor discharge temperature, which can lead to inefficient refrigerant transportation and operational issues.

Innovation Solution

Incorporating a liquid injection pipe in the outdoor liquid-refrigerant pipe to branch part of the refrigerant and feed it to the compressor, along with a refrigerant return pipe and cooler, to maintain a stable two-phase state and control the compressor discharge temperature.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the opening degree of the indoor expansion valve is temporarily increased to decrease the discharge temperature, then the discharge temperature is reduced, but the refrigerant state in the liquid-refrigerant connection pipe varies and the desirable gas-liquid two-phase state cannot be obtained

Engineering Contradiction:
Improvecompressor discharge temperatureVSAvoidrefrigerant state in liquid-refrigerant connection pipe
Core Design Contradiction:
TemperatureVSStability of the object's composition

Solution Approach 1:

The patent introduces a liquid injection pipe as an intermediary component that branches from the outdoor liquid-refrigerant pipe and feeds liquid refrigerant directly to the compressor suction side. This intermediary system allows temperature control of the compressor discharge without affecting the indoor expansion valve operation, thereby maintaining the desirable gas-liquid two-phase state in the liquid-refrigerant connection pipe while suppressing excessive discharge temperature increases

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent segments the refrigerant control system into multiple independent pathways: the main liquid-refrigerant connection pipe for transporting refrigerant in two-phase state to indoor units, and a separate liquid injection pipe for controlling compressor discharge temperature by injecting liquid refrigerant directly to the suction side. This segmentation allows independent optimization of each function without mutual interference

Inventive Principle:
Principle #1Segmentation

2Productivity

If the refrigerant is transported in the two-phase state through the liquid-refrigerant connection pipe, then efficient refrigerant transportation is achieved, but the compressor discharge temperature excessively increases

Engineering Contradiction:
Improverefrigerant transportation efficiencyVSAvoidcompressor discharge temperature
Core Design Contradiction:
ProductivityVSTemperature

Solution Approach 1:

The liquid injection pipe serves as an intermediary cooling system that injects liquid refrigerant directly to the compressor suction side, providing targeted cooling without disrupting the two-phase refrigerant transportation in the liquid-refrigerant connection pipe. This allows efficient refrigerant transportation to be maintained while suppressing excessive discharge temperature increases through the intermediary cooling pathway

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies local quality by providing targeted cooling only at the compressor suction side through the liquid injection pipe, rather than cooling the entire refrigerant circulation system. This localized cooling approach maintains the two-phase state in the liquid-refrigerant connection pipe for efficient transportation while specifically addressing the discharge temperature issue at the compressor location

Inventive Principle:
Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution ensures reliable transportation of refrigerant in a two-phase state while preventing excessive compressor discharge temperature increases, maintaining efficient operation and refrigerant flow.

Implementation Method 1

a liquid-pressure adjustment expansion valve that decompresses a refrigerant so that the refrigerant flowing through the liquid-refrigerant connection pipe is in a gas-liquid two-phase state

Methodology Applied
Scientific EffectDecompression: Depressurisation

Implementation Method 2

the liquid injection pipe is provided in the portion of the outdoor liquid-refrigerant pipe on the side of the outdoor heat exchanger with respect to the liquid-pressure adjustment expansion valve to branch part of the refrigerant flowing through the outdoor liquid-refrigerant pipe and feed the refrigerant to the compressor

Methodology Applied
Scientific EffectFluid flow branching:

Implementation Method 3

a refrigerant cooler that cools the refrigerant flowing through a portion of the outdoor liquid-refrigerant pipe

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Data Source

PatentEP3521720B1Air-conditioning apparatus
Publication Date: 2021.06.02 DAIKIN INDUSTRIES LTD
  • EP3521720B1 patent drawingFigure 1
  • EP3521720B1 patent drawingFigure 2
  • EP3521720B1 patent drawingFigure 3

AI summary

An air conditioner, in which a liquid-pressure adjustment expansion valve that decompresses a refrigerant so that the refrigerant flowing through a liquid-refrigerant connection pipe is in a gas-liquid two-phase state is provided in an outdoor liquid-refrigerant pipe that connects a liquid-side end of an outdoor heat exchanger to the liquid-refrigerant connection pipe, properly transports the refrigerant in a two-phase state while suppressing an increase in a discharge temperature of a compressor. A liquid injection pipe (46) that branches part of a refrigerant flowing through an outdoor liquid-refrigerant pipe (34) and feeds the branched refrigerant to a compressor (21) is connected to a portion of the outdoor liquid-refrigerant pipe (34) on a side of an outdoor heat exchanger (23) with respect to a liquid-pressure adjustment expansion valve (26).